Which characteristic of alcohol makes it less effective over time?

The characteristic of alcohol that makes it less effective over time is its evaporation rate. Alcohols, particularly those used as disinfectants, can evaporate quickly when exposed to air. This rapid evaporation can reduce the concentration of the alcohol on surfaces or in solutions, leading to decreased efficacy. For example, when alcohol is applied to a surface, if it evaporates too quickly, there may not be sufficient contact time to effectively kill bacteria or viruses. Maintaining an appropriate concentration for the required duration is crucial for its antimicrobial properties, and high evaporation rates can compromise this.

Understanding the evaporation rate is important for practical applications, such as sanitation and disinfection protocols. When using alcohol-based products, ensuring that they remain wet on the surface for an adequate period is essential for maximizing their effectiveness. Other characteristics like viscosity, solubility, and biochemical breakdown might influence various properties of alcohol but do not specifically address this decline in effectiveness due to evaporation.